Electron discharge tube apparatus



June 17, 1952 G. DIEMER ELECTRON Di SCI-IARGE TUBE APPARATUS Filed July 28, 1949 INVENTOR. HZSINl/SDILMEB Patented June 17, 1952 ELECTRON DISCHARGE TUBE APPARATUS Gesinus Diemer, Eindhoven, Netherlands, as-

signor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application July 28, 1949, Serial No. 107,288 In the Netherlands September 9, 1948 This invention relates to circuit arrangements for producing, amplifying or modulating electrical waves of a length of the order of some decimetres or less, comprising an electric discharge tube in which the electron beam is deflected by interaction with a travelling wave. The invention furthermore relates to a tube for use in such a circuit arrangement.

In known devices a pencil-shaped electron beam is deflected by interaction with two or more spiral-shaped conductors, between which the electron beam moves, or an electron beam moving along the surface of a circular cylinder is deflected between a spiral-shaped conductor and a conductive cylinder. Such electron beams can only carry a small current if no additional steps are taken to avoid stray of the beam.

According to the invention, in a device for producing, amplifying or modulating waves of a length of the order of some few decimetres or less, in which an electron beam is deflected by interaction with a travelling wave, the electron beam is a flat, disc-shaped beam which emanates from a cylindrical cathode which, if desired, is surrounded by one or more grids, whilst the deflection electrodes along which the travelling wave moves are constituted by two flat spirals surrounding the first-mentioned electrode system or by a single flat spiral provided opposite a flat conductive plate.

In order to ensure that the radial velocity of the electron beam and of the wave are equal, the ratio between pitch and circumference must have a constant value; this condition is only fulfilled by a logarithmic spiral. electrode is preferably shaped in this form, the

Consequently, the

4 Claims. (01. 315-39) initial pitch of the spiral being chosen to be small with respect to the initial radius in order to obtain the maximum number of turns. The ratio between the largest and the smallest radius is preferably equal to e, the base of the natural logarithm. The spiral thus fulfills the equation:

example will now be described with reference to the accompanying drawings in which:

Fig. 1 is a sectional view of the tube at right angles to the axis of the electrode system takenv along the line l-l of Fig. 2 and Fig. 2 is a vertical sectional view, partially in 2 elevation, through the axis of the tube taken along the line Hl I of Fig. 1.

Referring to the accompanying drawings, reference numeral I designates the glass envelope of the tube, in the axis of which a cylindrical incandescent cathode 2 of 5 mms. diameter is provided. The incandescent cathode 2 is surrounded by a control-grid 3 and a screen-grid 4, each of which is constituted by eight rods joined at the upper and lower ends by means of rings. The deflection electrodes consist of two strips 5 wound to form a logarithmic spiral and secured in two mica plates 1 with the use of short supporting rods. The anode system is made of two narrow strips 6, behind which a screen electrode 8 is provided. The two strips 5 and the strips 6 are separately brought out through the tube envelope I.

What I claim is:

1. An electron discharge tube of the traveling wave type comprising a cylindrical cathode source of electrons, a control grid located in the path of the electrons and surrounding said cathode, electron collecting means surrounding said cathode source'and control grid and spaced from said control grid, and a deflecting electrode system interposed between said control grid and said collecting means, said deflecting system comprising a planar traveling wave electrode interposed between said control grid and said collecting means and having a spiral section transverse to the axis of the cathode source and a second planar electrode interposed between said control grid and said collecting means and arranged substantially parallel to said first planar electrode and spaced therefrom.

2. An electron discharge tube of the traveling wave type comprising a cylindrical cathode source of electrons, a control grid located in the path of the electrons and surrounding said cathode, electron collecting means surrounding said cathode source and control grid and spaced from said control grid, and a deflecting electrode system interposed between said control grid and said collecting means, said deflecting system comprising a planar traveling Wave electrode interposed between said control grid and said collecting means and having a logarithmic spiral section transverse to the axis of the cathode source and a second planar electrode interposed source of electrons, a control grid located in the path of the electrons and surrounding said cathode, electron collecting means surrounding said cathode source and control grid and spaced from said control grid, and a deflecting electrode system interposed between said control grid and said collecting means, said deflecting system 4. An electron discharge tubeof the traveling wave type comprising a cylindrical cathode source of electrons, a control grid located. inithet path of the electrons and surrounding said cathode, electron-collecting means surrounding said cathode source and controlrgrid and spaced -from said control grid, and a deflecting-electrode system interposedbetween said control gridand said collecting means, said deflecting system comprising a first planar traveling waveelectrode interposed between said control grid and said collecting means and a second planar traveling wave electrode interposed between said control grid and said collecting means and arranged substantially parallel to said first planar electrode and spaced therefrom, said first traveling wave electrode having a spiral section'transverse to the axis of the cathode source, said spiral section having an initial pitch smaller than the initial radius thereof.

GESINUS DIEMER.

REFERENCES CITED The following references are of record in the file-of this patent:

'UNITED STATES PATENTS Germany May 7, 1932 

